Development and testing of a quantitative food frequency questionnaire for use in Kerala, India.

OBJECTIVE To develop and test a food frequency questionnaire (FFQ) for use in rural areas of Kerala, India. DESIGN Based on food use and market surveys of the study area, a quantitative 81-item interviewer-administered FFQ was developed. A validation study was conducted consisting of 24-h diet recalls (24HR) administered on 8 days randomly selected over an entire year and two administrations of the FFQ, one at the beginning of the 1-year period and the other at the end. FFQ and 24HR-derived nutrient scores were compared using correlation and regression analyses and by examining differences in the nutrient scores. SETTING Rural villages in Ernakulum district, Kerala, South India. SUBJECTS In each of 30 households, the male head of household and female food preparer were enrolled. RESULTS Pearson (parametric) correlation coefficients (r(p)) averaged about 0.50 in comparing nutrient scores derived from the 24HR with those from the first FFQ and about 0.55 in comparing the second FFQ. On average, Spearman correlation coefficients (r(s)) were slightly lower than the r(p) in comparing the scores derived from the first FFQ, but virtually identical for the second FFQ. Regression analyses indicated better agreement in the comparison of the 24HR-derived scores with the first FFQ than the second FFQ. Difference scores, however, tended to be larger in comparing the first FFQ scores with the 24HR. CONCLUSIONS This FFQ produces results broadly comparable to those used in Europe and North America, indicating its suitability for comparing exposures within a study population in reference to health-related endpoints.